The present invention relates to a modular gas adsorber assembly. Prior gas adsorbers conventionally comprise metal vessels which are filled-in by a given amount of an adsorbing material forming, inside the vessel, a sieve, allowing to separate one or more gases from a gas mixture, to provide, at the outlet of the vessel, a new and different gas mixture based on preset parameters, and free of other undesired substances, based on the type of used process and adsorbing material. Said prior adsorbers have the drawback that they are made with a preset constructional volume, dependent on the amount and purity of the end gas stream. Thus, said prior adsorbers must be specifically designed depending on a client requirement, which requires a comparatively high designing labor and use of different adsorbing materials, for meeting said well defined client requirements.